I've noticed that as the Arty Battalion and the Bomber Squadron are upgraded, they receive a boost to their damage and splash in addition to the boost they give to resource income if used. How much of an increase are the damage and splash given per building level? I know WG likes their hidden stats, but it'd be beneficial to clans if they have a way in-game (or not-so-in-game, at least) of knowing the average damage for each.

If these stats are already posted somewhere in the forums or elsewhere, can someone direct me over that way?